Even though it was a tiny increase, it was an improvement over February, when restaurants saw same-store sales fall 5 percent, according to data released by Black Box Intelligence and People Report, both Dallas-based market research firms owned by Thomas Doolin & Associates.

The sales data is based on figures from nearly 15,000 casual, upscale, fast-casual and family-dining restaurants across the country.

An early Easter helped lift March sales, but "we remain in a fragile sales environment," Bill Schaffler, president of Black Box Intelligence and People Report, said in a press release. Overall, first-quarter sales declined 1.3 percent.